import 'dart:io';

void main(List<String> args) {
 
   print("休眠开始");
  sleepSeconds1(3);
  print("休眠结束");
  
}

sleepSeconds(int seconds){
  
  sleep(Duration(seconds: seconds));
  
}

Future sleepSeconds1(int seconds){
  
  return Future<dynamic>((){
     sleep(Duration(seconds: seconds));
    // return "";
  });
  
}